It is incredible to the inventor that; for the thousands of years man has used sail power to propel boats that the most aerodynamically efficient forms in use today should be among the oldest. In the rig in most common use today the sail is essentially supported at the windward portion of the mast. In the sailing maneuver in which most time is consumed; tacking or beating, the resultant airfoil configuration is roughly equivalent to the placement of an 18" dia. piece of sewer pipe along the top of the wing of a 747 at the forward edge and then expecting it to fly. The hereinafter disclosed invention provides an economical and convenient means whereby sails of conventional, single web form are positioned in the more efficient leeward position with respect to the mast.